import React from 'react';
import ReactDOM from 'react-dom';

class App extends React.Component {
  state = {list: new Array(10000).fill(0)};

  render() {
    return (
      <ul>
        <input type="text"/>
        <button>add</button>
        {
          this.state.list.map((item,index)=><li key={index}>{item}</li>)
        }
      </ul>
    )
  }
}

ReactDOM.render(<App/>, document.getElementById('root'));
